fix(android_installs): restrict zero filtering to trailing tail only

[TimeToBuildBob]

Summary

Fixes the bug identified by the Codex bot in PR #19 review comment discussion_r3566750142.

Problem: parse_report() filtered out any row with value "0", but the intent was to suppress only Play Store's unfinalized trailing days (which report as 0). An internal zero (e.g. 2026-07-06 in the rebuild) is silently dropped, creating a gap in the install series that analyze_stats._load_data() then interpolates over.

Fix: Collect all rows, then strip only the trailing-zero suffix in a second pass. This preserves valid internal zeros while still suppressing Play's unfinalized-tail noise.

# Before: drops ALL zeros
if date and value and value != "0":
    out[date] = value

# After: keep all, trim trailing zeros only
if date and value:
    out[date] = value
dates = sorted(out)
while dates and out[dates[-1]] == "0":
    del out[dates.pop()]